Power transmission



D. B. GARDINER POIER TRANSMISSION Feb. 21, 1950 3 Sheets-Sheet 1 FilidJan. 25, 1947 FIG. I

IIIII INVENTOR.

DUNCAN B. GARDINER BY ATTORN EY Feb. 21, 1950 n, Dm 2,498,543.

POWER TRANSISSION Filod Jan. 25, 1947 I 3 Sheets-Sheet 2 FIG. 6

mmvron. DUNCAN B. GARDINER ATTORNEY Feb. 21, 1950 GARDM'R 2,498,543

- POWER TRANSMISSION Filed Jan. 25. 1947 3 Sheets-Sheet 3 FIG. 9

FIG. I0

uvmvrmm DUNCAN B. GARDINER BY ATTORNEY Patented Feb. 21, 1950 2,498,543rowan TRANSMISSION Duncan B. Gardiner, Detroit, Mich., asslgnor toVickers Incorporated, Detroit, Mich., a corporation of MichiganApplication January 25, 1947, Serial No. 724,443

11 Claims.

This invention relates to power transmissions, particularly to those ofthe type comprising two or more fluid pressure energy translatingdevices, one of which may function as a pump and another as a fluidmotor.

The invention is more particularly concerned with a hydraulic powertransmission system designed for imparting a reciprocating movement to aslide or table such as is used for instance on grinders. In hydraulictransmissions of this type, a continuous reciprocating movement isimparted to the table or slide upon which the work element or the toolelement is carried until the work is ground to the required size. tomaryto provide means for controlling the speed of the table, for controllingthe stroke length and for automatic reversal at each end of the stroke.In addition, means may be provided for controlling. the acceleration anddeceleration of the slide at the start and end of each stroke.

It is an object of the present invention to provide a power transmissionsystem of the type particularly adapted for operating grinders andhaving an improved means for controlling the deceleration andacceleration at reversal of the hydraulically actuated slide or table.

It is a further object of the present invention to provide a unitarycontrol panel for use in hydraulic power transmissions of the above typewherein is incorporated a minimum of control valves for providingcontinuous reciprocating strokes of the table or slide, controlled speedof the stroke, automatic reversal at each end of the stroke, andcontrolled acceleration and de- I celeration at the start and end ofeach table stroke.

Further objects and advantages of the present invention will be apparentfrom the .following description, reference being had to the accompanyingdrawings wherein a preferred form of the present invention is clearlyshown.

In the drawings:

Figure 1 is a sectional view of a preferred form of the presentinvention.

Figure 2 is a top view of the present invention.

Figure 3 is a left side view of the present invention.

Figure'4 is a right side view of the present invention.

Figure 5 is a bottom view of th present invention.

Figure 6 is a view taken from line 66 of Figure 3.

It is cus- 2 ti Figure '7 is a rear view of the present inven- Figure 8is a view taken from line 8 -8 of Figure 6 and Figure 1.

Figure 9 is a diagrammatic view illustrating the circuit of the paneltogether with the associated elements of a complete power transmissionsystem showing the parts in position during operation.

Figure 10 is a view corresponding to Figure 9,

but showing the parts in another position during operation.

Referring now to Figure 6, there is shown a unitary control panel Incomprising a body I2 within which is mounted all of the valvingmechanism necessary for controlling the automatic reversal, speed andacceleration and deceleration of a fluid motor 14 shown in Figures 9 and10, the latter of which is adapted to drive a grinder table or slide,not shown. For the purpose of controlling the directional movement ofthe motor l4, a reversing valve I6 is reciprocably mounted in alongitudinal bore l8 extending completely across the body l2. The boreI8 is provided with a centrally located groove forming a pressure port20, with grooves on the right and left side of groove 20 which,respectively, form motor ports 22 and 24 and with grooves spaced apartfrom the motor ports forming tank ports 26 and 28. The reversin valve I6is provided with a large centrally located land 30 which cooperates withlands 32 and 34 spaced apart from land 30 on the left and right sidethereof, respectively, for alternately connecting the pressure port 20and tank port 28 to the cylinder ports 22 and 24. The valve I6 is alsoprovided with extreme right and left end'lands 36 and 38, respectively,which acts as guides for the valve IS. The valve I6 is also providedwith a plurality of transverse ports 40 located between lands 34 and 36which are connected by means of a longitudinal passage 42 within thevalve l6 to another plurality of transverse ports 44 located betweenlands 32 and 38. Thus, with valve l6 shifted completely to the right,fluidreturning from the motor [4 to the cylinder port 22 is directedthrough the cooperation of lands 30 and 34 to the tank port 26 and fromthe tank port 26 to the tank port 28 by means of transverse ports 40,longitudinal passage 42 and transverse ports 44.

The reversing valve I6 is adapted to be actuated hydraulically under thecontrol of a pilot valve 46, the latter of which is formed on one partof a spool 48 reciprocably mounted in a longitudinal bore 50 extendingcompletely across 3 the body I2. Formed on the left side of the spool48, so as to be reciprocable with pilot valve 46, is a combinedacceleration and deceleration valve 52. The bore 58 is provided with alarge centrally located groove forming a tank port 54 and spaced apartgrooves to the right thereof forming ports 56, 58, 60, and 6|, thelatter of which forms an extreme right end chamber. Port 56 is connectedto the left end of bore I8 containing reversing valve I6, port 60 isconnected to the right end thereof and port 58 is adapted to becontinuously connected to a source of pressure fluid. It is the functionof the pilot valve 46 to alternately connect the pressure port 58 andthe tank port 54 to the ports 56 and 60 so as to shift reversing valve60 rightwardly or leftwardly near the end of each motor stroke toreverse the directional movement of the motor. For this purpose, plates62 and 64 are respectively suitably bolted to the right and left sidesof the body I2 containing passages which cooperate with passagesconstructed in the body I2 in the following manner.

Referring now to Figures 1 and 6, the right plate 62 is provided with avertical passage -66 closed at its upper end by a suitable plug 61. Thepassage 66 terminates at a point of intersection with a horizontalpassage 68 which is adapted to register with the right end of bore I8.The left side plate 64 is also provided with a vertical and a horizontalpassage I and I2, respectively, the latter of which is adapted toregister with the left end of bore I8 while the open end of the formeris closed by a suitable plug 13.

For the purpose of connecting vertical passage 66 to the groove formingport 60, a passage 14 is constructed from the rear of the right plate'62 which intersects vertical passage 66 and which is closed at its openend by a plug 16 shown in Figure 7. A horizontal passage I8 in plate 62intersecting passage 14 is adapted to register with a. longitudinalpassage 80 in the body I2 constructed from the right side thereof whichintersects a passage 82 constructed from the rear of body I2. Thepassage 82 intersects the groove forming port 60. As shown in Figure 7,the open end of passage 82 is closed at the rear end of body I2 by aplug 83.

For the purpose of connecting the groove form'- ing port 56 to the leftend of bore I8, a passage 84 is constructed from the rear of the leftplate 64 which intersects vertical passage I0 and which is closed at itsopen end by a plug 86 shown in Figure 7. A horizontal passage 88 in theleft plate 64 intersecting passage 84 is adapted .to register with alongitudinal passage 90 constructed from the left side of body I2. Thepassage 90 intersects a passage 92 constructed from the rear of body I2which intersects the groove.

forming port 56. As shown in Figure 7, the open end of passage 92 isclosed at the rear of the body I2 by means of the plug 93.

Referring now to Figure 6, the pilot valve portion 46 of spool 48 isprovided with an extreme right end land 94 and a land 96 to the leftthereof and spaced apart therefrom. The spool 48 is provided withenlarged bores at the extreme right and left ends thereof indicated bythe numerals 88 and I00 which are connected to each other by a.longitudinal passage I02 in said spool. The spool 48 is normallymaintained in the center position shown in Figure 6 by means ofduplicate springs I04 and I06, 2. portion of each of which is mounted inright and left end, hollow and cup- Ill) shaped spring retainers I08 andH0, the latter of which are mounted in the enlarged bores 98 and I00 ofspool 48. The right and left end spring retainers are provided,respectively, with a port I II and a port I I3 adapted to register withlongitudinal passage I02. The retainers I08 and H0 are provided withflanges H2 and H4, respectively, which are, respectively, adapted toabut shoulders I I 6 and I I 8 in order to normally center the spool 48within the bore 58. The opposite ends of the springs I04 and I86 aremounted in bores provided for that purpose in the right and left endplates 62 and 64.

As shown in Figure 6, the right spring retainer I08 is provided with aplurality of slots I 20 which in the position shown, or when spool 48 isshifted leftwardly, registers with a plurality of flats I22 constructedin and near the end of spool 48 to form a means of communication betweenthe groove forming port and the extreme right end chamber 6|. When spool48 is shifted rightwardly, the retainer I08 is also shifted rightwardlyby the spool 48 and the slot I28 and the flats I22 shift out of registrywith the groove 60 to close communication between the groove 60 and theextreme right end groove of the bore 50 formin chamber 6|.

The spool 48 is also provided with a centrally located transverse boreI24 extending through the spool which connects the longitudinal passageI02 with the enlarged centrally located groove of the bore forming tankport 54. Thus, upon spool 48 shifting rightwardly or leftwardly, thecorresponding extreme ends of the bore 50 are placed in communicationwith the tank port 54 to permit proper shifting of the spool 48. Itshould also be noted that in the center position of the spool 48 notonly are the extreme ends of the bore 50 in communication with tank port54 but also the opposite ends of bore I8.

The left end portion of spool 48 forming the acceleration anddeceleration valve 52 is constructed with an extreme left end land I25,a land I26 spaced apart therefrom to the right thereof, and a pluralityof notches I 28. The notches I28 control the flow of fluid from a groovein the bore 50 forming a return port I30 to the tank port 54. As willhereinafter be described, all fluid discharged from either end of themotor I4 must pass through the return port I38 and the tank port 54.When the spool 48 is shifted rightwardly from the center position nearthe end of one motor stroke, the left end of the notches I28 willgradually pass over the return port I36 to gradually restrict the flowof fluid from the motor and decelerate the same When the spool 48 isshifted from the center position to the left near the end of theopposite motor stroke, the right end of the notches I28 gradually willpass over the tank port 54 to gradually restrict the flow of fluid fromthe motor I4 and decelerate same. In addition, the notches I28 of theacceleration and deceleration valve 52 and the lands 94 and 96 of thepilot valve 46 are so arranged on the spool 48 that, just before thereturn port I 30 or the tank port 54 would be closed, the pilot valve 46reverses the connections to the reversing valve spool I6 to reverse thedirection of the motor I4. Upon reversal of the motor I4, the spool 48is designed to follow the reverse stroke of the motor I4 until centeredso that the return or tank port, 1. e., whichever port was graduallclosed to decelerate the motor I4, will be gradually reopened to thedischarge from the opposite end of the motor to smoothly accelerate thelatter. When the spool 48 is centered, as shown in Figure 6, the notchesI28 permit free flow of fluid from the return port I30 to the tank port54.

The spool 48 is adapted to be actuated near each end of the motor strokeby the usual table dog arrangement (not shown) in the well-known manner.For this purpose, a ball-ended rod I82 fits into the bore I24 of thespool 48 and is secured to a rotatable shaft I36 which is mounted in abore I38 extending completely through the body I2 from the rear to thefront thereof. A lever arm I40 adapted to be contacted by the dogsassociated with the sliding table is pivotally connected to the shaftI36 for reciprocation of the latter. Connected to the portion of theshaft I36 which extends from the front of the body I2 is a lever I42(Figure 1) for manual operation of the valve spool 48 during set-up andfor stopping the motor during operation of the grinding process. Aspreviously stated, during normal operation of the grinding process, thereturn or tank port is never completely closed. However, it may beclearly seen that, if the spool 48 was manually shifted by the lever I42to completely close the return or tank port, discharge flow from themotor I4 would be blocked and the motor would stop.

Suitably mounted in a bore I44 constructed completely across the bodyI2, but on a different plane than bores I8 and 50, is control valvemechanism for maintaining a constant pressure drop across a throttle I46mounted in a bore I48 extending from the front to the rear of the panelI0.

The control valve mechanism consists of a compensating valve I50comprising a piston I52 reciprocably mounted in the bore I44, saidpiston being provided with a stem I54 connected thereto having two landsI56 and I58. The stem I54 is reciprocalble in a bore I59 of a sleeve I60mounted in the bore I 44.

The sleeve I60 is provided with an annular port I62 and a passage I64connecting said port to the bore I59 and spaced apart therefrom anannular port I66 and a passage I68 which connects the port I66 to thebore I59. A passage I extending completely lengthwise through the sleeveI60 intersects passage I64 but not passage I68.

The port I62 is directly connected to an external connection pressureport I12 located in the rear of the body I2 by means of a passage I18.The port I66 is connected to an externally located tank port I14 in therear of the body I2 by means of a passage I16 constructed from the frontof the body (Figure 4), the open end of which is closed by a plug I11(Figure l). The passage I16 intersects a passage I18 constructed fromthe right side of the body I2, the latter passage of which intersects apassa e I80 connected to external tank port I14. The passage I80 alsoconnects the external tank port I14 with an annular port I82 formed in asleeve I84 mounted in bore I44. The sleeve I84 has a longitudinal boreI86, the latter of which is connected to the port I82 by a passage I81.

The bore I86 is threaded near its right end for the reception of a seatmember I88 for a pilot relief valve I90. The pilot relief valve I90 isnormally maintained on a seat I92 formed in the seat member I88 by meansof a spring I94 of predetermined resistance mounted in the opposite endof bore I86, the latter of which is also 6 threaded for the reception ofan adjusting screw I88. The left side plate 64 contains a bore I86adapted to register with the bore I88 of sleeve I84 so that theresistance of the spring I94 may be changed by adjusting screw I96without removing the side plate 64. The passage I81 in the sleeve I84connects the port I82 to an exhaust chamber 200 formed in bore I86between the right end of the adjusting screw I86 and the seat memberI88.

The piston I52 of compensating valve I50 is adapted to be responsive topressure ahead of the throttle in a chamber 204 formed in the bore I44between the left end of sleeve I60 and. the right side of piston I52.The piston I52 is adapted to be responsive to pressure beyond thethrottle in a chamber 208 formed in the bore I44 between the left sideof piston I52 and the right end of the seat member I88. The chamber 206is in communication with the pilot relief valve I by means of a bore 208extending through the seat member I88 at the extreme left end of whichis formed the seat I92. Thus, upon a predetermined pressure arising inthe system as determined by the resistance of spring I94, the valve I90will be shifted to connect chamber 206 to exhaust chamber 200, and adifferential pressure will be created in the chamber 204 and 206. Thegreater pressureexisting in chamber 204 is sufllcient-to shift thecompensating valve I50 against the slight resistance of a spring 2I0biasing the compensating valve I50 to the closed position, and land I56will open fully the port I82 to port I66 so as to relieve all pressurefluid to the external tank port I14. Whenever the pressure in the systemis below the setting of spring I94, the resistance of the spring 2! of 4compensating valve I50 will determine the pressure drop across thethrottle I46.

The pressure ahead of the throttle is existent in chamber 204 by meansof the pressure port I12, the pressure passage I13, and the groove I62,passage I64 and passage I10 of sleeve I06.

Pressure beyond the throttle I46 is in communication with chamber 206 inthe following manner: The pressure groove I62 of the compensating valveI50 is connected to the throttle bore I48 by means of a passage 2I2constructed from the top of the body I2 and which extends downwardly toa point of intersection with a passage 2I4 constructed from the rightside of body I2 and which intersects the throttle bore I48. The verticalpassage 2I2 which is closed at its upper end by a plug 2I5 alsointersects the pressure port 58 controlled by pilot valve 48 and theport I62 formed in sleeve I60. It should be noted that in this mannerpressure fluid entering the external pressure port I12 is not onlydelivered to the throttle I46, but also to th compensating valve I50where it has an influence on piston I52 within chamber 204 and also isdelivered to the pressure port 58 of pilot valve 46 from where the pilotvalve 46 may direct the same to either end of the reversing valve. Fromthe throttle bore I48, pressure fluid is directed to the chamber 206 ofcompensating valve I50 by means of a passage 2"; constructed from thebottom of body I2 which intersects the pressure port 20 of reversingvalve I6 and is connected to the throttle bore I48. A passage 2I8constructed from the bottom of body I2 also intersects the pressure port20 and is connected to a port 220 formed in the sleeve I84. The port 220is connected to chamber 206 by means of a passage 222 in the sleevemember I84. The passages 2I6 and 2| 8 are closed at their open ends byplugs 2H and 2| 8. The flow through throttle I46 may be regulated bymeans of a manually operated dial 224 suitably connected to the throttieas shown in Figure 1. The two motor ports 22 and 24 are respectivelydirectly connected to the externally located motor ports 226 and 228 inthe rear of the body I2. respectively, by means of passages 230 and 232.

The reversing valve I6 is designed to always direct fluid dischargingfrom either end of the motor I4 to the return port I of the accelerationand deceleration valve 52. For this purpose a vertical passage 234 isconstructed from the top of the body I2 which intersects port I 30 ofvalve 52 and continues to a point of intersection with the tank port 28of reversing valve I6. The passage 234 intersects the groove I30 of bore50, but does not intersect bore I44 and is closed at its open end by aplug 236 (Figure 1) For the purpose of directing fluid to the externaltank port I14 from the groove I30 and groove 54 of bore 50, a passage238 is constructed from the front of the body I2 which intersects thegroove 54 forming the main tank port of bore 50 and also intersects thegroove forming the annular port I82 of sleeve I84. As the passage I80 isconnected to the external tank port I14 and intersects port I82 ofsleeve I84, it may be clearly seen that fluid is directed from the tankport 54 to the external tank port I14 by means of passage 238, port I82of sleeve I84, and passage I80. The passage 238 is closed at its openend by means of a plug 239.

Due to the fact that the spool 48 returns to a centrally locatedposition after the reversing valve has shifted completely to reverse thedirection of the motor I4, both ends of bore I8 containing the reversingvalve I6 will be connected to the external tank port I14. Because of theabsence of pressure at one end or the other of the bore I8 to maintainthe reversing valve I6 in the position last shifted to, a friction padindicated generally by the numeral 240 and shown more clearly in Figure8 is provided to perform this function. The assembly 240 which ismounted in a bore 242 extending from the rear of the body I2 and whichintersects the left end of the bore I8 comprises a chamfered piston 243adapted to frictionally engage the left end of valve I6 by means of aspring 244 of slight resistance mounted in a plug 246 which is threadedinto bore 242.

Referring now to Figures 9 and 10, these diagrams represent the internalcircuit of the panel I0 together with the other elements of a typicalhydraulic power transmission system. Thus, there is represented a tank250 and a pump 252 having a suction conduit 254 and a delivery conduit256, the latter of which is connected to the external pressure port I12of the panel I0. The external tank port I14 is connected to the tank 250by means of a conduit 258. The external motor ports 226 and 228 areconnected to the opposite ends of the motor I4 by means of conduits 260and 262. cylinder 264 within which is reciprocably mounted a piston 266which is connected to a piston rod 268 extending from both ends of thecylinder 264. The motor I4 is adapted to drive The motor I4 comprises aa grinder table having dogs associated therewith f not shown) forcontacting the lever arm M0 at each end of the table stroke.

The internal circuit of the panel for purposes of convenience isillustrated in the following 8 manner. The right and left ends of thereversing valve I6 are respectively connected to the ports 60 and 56 ofthe pilot valve 46 by means of conduits 62' and 10'. A conduit 234'connects the return port I30 of the valve '52 to the tank port 28 ofreversing valve I6 and a conduit 238' connects the tank port 54 of bore50 to the external tank port I14 and to the exhaust port I82 of therelief valve mechanism. A conduit 2I2' connects the external pressureport I 12 to the port I62 of compensating valve I50 and also to the port58 of pilot valve 46. A conduit 2I6' connects the throttle I46 to theexternal pressure port I12 and also to the pressure port 20 of reversingvalve I6. A conduit 2I8' connects the port 220 of the sleeve member I84to the pressure port 20 of reversing valve I6, and a conduit I18connects the port I66 of compensating valve I50 to the passage 238'. Theexternal motor ports 226 and 228 are respectively connected to the ports24 and 22 of the reversing valve I6 by means of conduits 232 and 230.

In operation, with the parts in the position Near the completion of therightward motor stroke, lever arm I40 was contacted and the spool 48shifted rightwardly to the position shown. During the shifting of thespool 48 rightwardly, the notches I 28 of the acceleration anddeceleration valve 52 gradually passed over the return port I30 so as togradually restrict the flow of fluid discharging from the motor throughconduit 262. By gradually restricting the flow of fluid discharging fromthe motor I4, the latter was smoothly decelerated.

Just before the return port I30 was'completely closed by the notches I28passing completely over said port, the land 94 of pilot valve 46 openedcommunication between the pressure port 58 thereof to the groove formingport 60. Port 60 is connected to the right end of 1 thereversing valveI6 and said valve immediatelyandflquickly shifted leftwardly becausethe; left end of the reversing valve is directly connectedto the tank250. Fluid displaced from the leftend of the reversing valve I6 wasdirected to the tank 250 by means of conduit 10', port 56 of pilot valve46, tank port 54, conduit 238', external tank port I14, and conduit 258.The reversing valve I6 by means of lands 30 and 34 immediately directedfluid to the right end of motor I4 to reverse the direction thereof.

As the motor I4 reverses its stroke, the lever I40 remains in contactwith the table dog, not shown, and the fluid now discharging from theleft end of the motor I4 must be discharged to tank 250 through thereturn port I and tank port 54 spaced along bore 50. As previouslystated, the port I30 had almost been closed by the notches I28 passingover the port I30 when the connections to the motor I4 were changed toreverse the direction of said motor. Consequently, as the lever I40follows the dog on the return stroke of the motor, the notches I28gradually reopen the return port I30 to gradually permit an increase inflow discharging from the motor to smoothly accelerate the same. Fluiddischarging from the left end of the motor I4 is returned to tank 250 bymeans of conduit 260, external port 226, passage 232, ports 24 and 28 ofreversing valve I6, passage 234, ports I30 and 54 of valve 52, passage238', external tank port I14 and conduit 258. When the spool 48 hasreturned to the center position shown in Figure 6,

the dog will lose contact with the lever I40 and the speed of the motorI4 will be regulated by the throttle I46 and compensating valve I50 inthe well-known manner.

The compensating valve I50 is adapted to maintain a. constant pressuredrop across the throttle I48 by being responsive to the pressure aheadof and beyond the throttle I48. Any tendency to create a pressure dropgreater than the resistance of spring 2 I is immediately reflected inchamber 204 causing the piston I52 to shift leftwardly and resulting inland I56 opening communication to port I62. The port I62 is opened toport I66 so that an amount of fluid will be exhausted to the tank 252sufficient to maintain the pressure drop across the throttle 246uniformly constant.

If at any time the pressure within the system increases to a valuedetermined by the resistance of spring I94, relief valve I90 will beshifted to connect chamber 206 to the tank 250 causing a differentialpressure to be created in the chambers 284 and 206 on opposite sides ofthe piston I52. This differential pressure results in piston I52shifting completely to the left. and the complete flow of excessivepressure fluid from the pump 252 will be exhausted through thecompensating valve I50 to the tank 250.

When the piston 266 of motor I4 nears the end of its leftward stroke,the lever I48 will be contacted by another dog, not shown, to shift thespool 48 leftwardly and. instead of the return port I80 graduallv beingclosed to discharging flow from the motor M as on the opposite stroke ofthe motor, the tank port 54 will gradually be closed by the land I26 andnotches I28. As the spool 48 is shifted leftwardly, the notches I28 willgradually pass over the tank port 54 and fluid discharging from the leftside of motor I 4 will gradually be restricted to smoothly deceleratethe motor. Any excess of fluid delivered by the pump 252 is exhausted totank 250 by means of the compensating valve I50.

Just before the notches I28 pass completely over the tank port 54, theland 96 of pilot valve 46 will open communication between pressure port58 and groove 56 which will permit pressure fluid to be directed bymeans of passage ID to the left end of the reversing valve I6 to shiftthe same rightwardly. Fluid discharging from the right end of reversingvalve I6 will be freely discharged to tank 250 by means of passage 62,groove 60, the flats H2 in spool 48 and the slots I20 of the rightspring retainer I08 from where fluid is directed to the interior of theretainer I08 through the port III. From the retainer I08 the fluid flowsthrough lon itudinal passage I02, central bore I24 of spool 48, tankport 54. passage 288', extern l tank port I, and conduit .258 to thetank 250.

The reversing valve I8 will now connect the pressure port 20 thereof tothe cylinder port 24 thereof, and pressure fluid will be directed fromthere by means of passage 232, external motor port 226, and conduit 260to the left end of the motor I4. As the motor I4 reverses itsdirectional movement, the lever I 40 will follow the dog not shown untilthe spool 48 is again centered.

It should be noted that the motor I4 will be smoothly accelerated byreason of the discharging fluid therefrom being gradually permitted toincrease in volume. This is accomplished by the notches I28 graduallyopening up the tank port 54 to the return port I 30. Fluid dischargingfrom the right end of the motor I4 is directed to the tank 250 by meansof conduit 282, external motor port 228, passage 230, motor port 22, andgroove 26 of reversing valve I6, the ports 40, longitudinal passage 42,and ports 44 of the reversing valve spool, port 28, passage 234', portsI30 and 54 of the valve 52, passage 238', external tank port "4, andconduit 258.

Thus, it should be noted that the valve 52 is designed to bothaccelerate and decelerate the motor I4. The panel is sodesigned that allfluid discharging from the motor must discharge to the tank through thereturn and tank ports, both of which are controlled by the accelerationand deceleration valve. On one stroke of the motor, the return port isslowly closed to decelerate the motor. Just before the return port iscompletely closed, the pilot valve will reverse the connections to thereversing valve and the reversing valve will reverse the direction ofthe motor. As the motor reverses its stroke, the return port isgradually reopened by the notches in the valve to smoothly acceleratethe motor. As the motor nears the end of this latter stroke, thedeceleration and acceleration valve will, by means of the notches in thespool, slowly close the tank port to discharging fluid from the motorand decelerate the same. Before the tank port is completely closed, thepilot valve will reverse the connections to the reversing valve and thelatter will shift to reverse the direction of the motor. As the motorreverses its stroke, the tank port will gradually be reopened by thenotches of the valve and the motor will be smoothly accelerated.

Thus, the acceleration and deceleration of the hydraulically actuatedmotor is accomplished in a novel manner without the use of adjustableorifices or adjustable valve travel which have been used in the'past tocontrol reversal speed.

In addition, the panel contains a minimum of valvular mechanism which inaddition to the above provides for automatic reversal and controlledspeed of the motor, and also provides maximum safe pressure protection.

While the form of embodiment of the invention as herein disclosedconstitutes a preferred form, it is to be understood that other formsmight be adopted, all coming within the scope of the claims whichfollow.

What is claimed is as follows:

1. A unitary control panel for use in a hydraulic power transmissionhaving a fluid pump and reversible fluid motor, said panel comprising incombination a body, a reversing valve shiftably mounted therein forreversing the flow of fluid to and from the motor, a pilot valveshiftably mounted therein adapted to be actuated in opposite directionsby the motor for controlling the reversing valve, a motor returnconnection, and a single valve means shiftably mounted within the i bodyfor automatically gradually closing said connection near the end of amotor stroke to decel erate the motor and for automatically graduallyreopening the same connection on the opposite stroke of the motor toaccelerate the latter.

2.-A unitary control panel for use in a hydraulic power transmissionhaving a fluid pump and reversible fluid motor, said panel comprising incombination a body, a reversing valve shiftably mounted therein forreversing the flow of fluid to and from the motor, a pilot valveshiftably mounted therein adapted to be actuated in opposite directionsby the motor for controlling the reversing valve, a motor returnconnection,

and a single valve means mechanically associated with the pilot valveshiftably mounted within the aeoaoea draulic power transmission having afluid pump and reversible fluid motor, said panel comprising incombination a body, a reversing valve shiftably mounted therein forreversing the flow of fluid to and from the motor, a pilot valveshiftably mounted therein adapted to be actuated in opposite directionsby the motor for controlling the reversing valve, a motor returnconnection, and a single valve means mechanically associated with thepilot valve shiftably mounted within the body for automaticallygradually closing said connection near the end of a motor stroke todecelerate the motor and for automatically gradually reopening the sameconnection to accelerate the motor after the reversing valve has shiftedcompletely to reverse the direction of the motor. 4. A unitary controlpanel for use in a hydraulic power transmission having a fluid pump andreversible fluid motor, said panel comprising in combination a body, areversing valve shiftably mounted therein for reversing the flow offluid to and from the motor, a pilot valve shiftably mounted thereinadapted to be actuated in opposite directions by the motor forcontrolling the 1 reversing valve, control valve mechanism within thebody for controlling the speed of the motor, a motor return connection,and a single valve means shiftably mounted within the body forautomatically gradually closing said connection near the end of a motorstroke to decelerate the motor and for automatically gradually reopeningthe same connection on the opposite stroke of the motor to acceleratethe latter.

5. A unitary control panel for use in a hydraulic power transmissionhaving a fluid pump and reversible fluid motor, said panel comprising incombination a body, a reversing valve shiftably mounted therein forreversing the flowv of fluid to and from the motor, a pilot valveshiftably mounted therein adapted to be actuated in opposite directionsby the motor for controlling the reversing valve, control valvemechanism within the body for controlling the speed of the motor, a'motor return connection, and a single valve means mechanicallyassociated with the pilot valve shiftably mounted within the body forautomatically gradually closing said connection near the end of a motorstroke to decelerate the motor and for automatically gradually reopeningthe same connection on the opposite stroke of the motor to acceleratethe latter.

6. A unitary control panel for use in a hydraulic power transmissionhaving a fluid pump and reversible fluid motor, said panel comprising incombinat on a body, a reversing valve shiftably mounted therein forreversing the flow of fluid to and from the motor, a pilot valveshiftably mounted therein adapted to be actuated in opposite directionsby the motor vfor controlling the reversing valve, control valvemechanism within the body for controlling the speed of the motor, amotor return connection, and a single valve means mechanicallyassociated with the pilot valve shiftably mounted within the body forautomatically gradually closing said connection near the end of a motorstroke to decelerate the motor and for automatically gradually reopeningthe same connection to accelerate the motor after the reversing valvehas shifted completely to reverse the direction of the motor.

7. A unitary control panel for use in a hydraulic power transmissionhaving a fluid pump and reversible fluid motor, said panel comprising incombination a body, a reversing valve shiftably mounted therein forreversing the flow of fluid to and from the motor, a pilot valveshiftably mounted therein adapted to be actuated in opposite directionsby the motor for controlling the reversing valve, control valve mechanism mounted within, the body for controlling the speed of the motorincluding an adjustable throttle and a compensating valve formaintaining a constant pressure drop across the throttle, a motor returnconnection, and a single valve means shiftably mounted within the bodyfor automatically gradually closing said connection near the end of amotor stroke to decelerate the motor and for automatically graduallyreopening the same connection on the opposite stroke of the motor toaccelerate the latter.

8. A unitary control panel for use in a hydraulic power transmissionhaving a fluid pump and reversible fluid motor, said panel comprising incombination a body, a reversing valve shiftably mounted therein forreversing the flow of fluid to and from the motor, a pilot valveshiftably mounted therein adapted to be actuated in opposite directionsby the motor for controlling the reversing valve, control valvemechanism mounted within the body for controlling the speed of the motorincluding an adjustable throttle and a compensating valve formaintaining a constant pressure drop across the throttle, pressureresponsive valve means associated with the compensating valve forcausing the compensating valve to also perform the function of a reliefvalve, a motor return connection, and a single valve means shiftablymounted within the body for automatically gradually closing saidconnection near the end of a motor stroke to decelerate the motor andfor automatically gradually reopening the same connection on theopposite stroke of the motor to, accelerate the 4 shifted in oppositedirections from the center position thereof by the motor forautomatically gradually closing said connection near the end of a motorstroke to decelerate the motor and for automatically gradually reopeningthe same connection on the opposite stroke of the motor to acceleratethe latter.

10. A unitary control panel for use in a hydraulic power transmissionhaving a fluid pump and reversible fluid motor, said panel comprising incombination a body having external connections for pressure supply andexhaust and two external motor connections, and said body having mountedtherein a reversing valve for alternately' connecting the pressure andexhaust connections to the two motor connections, a pilot valve forcontrolling the reversing valve, and a 75 single valve means including amotor retum conaceam nection in communication with the external exhaustconnection for automatically gradually closing the return connectionnear the end or a motor stroke to decelerate the motor and forautomatically gradually reopening the return connection on the oppositestroke of the motor to accelerate the latter, said pilot valve and valvemeans being mechanically connected, spring biased to the center positionand adapted to be simultaneously shifted in opposite directions past thecenter position thereof by the motor near the end of each stroke of thelatter.

11. A unitary control panel for use in a hydraulic power transmissionhaving a fluid pump and reversible fluid motor, said panel comprising incombination a body, a reversing valve shiftably mounted therein forreversing the flow of fluid to and from the motor, a pilot valveshiftably mounted therein adapted to be actuated in opposite directionsby the motor for controlling the reversing valve, a motor return con-REFERENCES orrnn The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Name Date Ewart Sept. 6, 1898 Fraser Aug. 27, 1935Twyman Dec. 23, 1941 Number

